ROS Resources: Documentation | Support | Discussion Forum | Service Status | Q&A answers.ros.org

SubT Challenge Hello World Post 5: Communications

SubT Challenge Hello World Post 5: Communications

SubTPost5
SubT Mapping Screen Cap

Hi All!

It is my pleasure to announce our fifth post in the SubT Challenge tutorial series! If you haven’t been keeping up, in this series of tutorials we walk you through how to build a competition software stack for the DARPA SubT Challenge Virtual Competition. In the past few weeks, the role of the Virtual Competition has increased greatly due to the fact that DARPA has pivoted to an all-virtual Cave Circuit event. The good news is that this set of tutorials covers all of the subsystems you need to start building a solution. The SubT Challenge Cave Circuit qualification deadline is September 15th, so you have ample time to gather a team and build out your software stack. With a top prize of $250,000 USD, it is more than worth your time to enter the Virtual Competition.

Further sweetening the pot in recent weeks, DARPA has added a number of simulated robotic platforms based on actual robots in the Systems Competition. If you’ve ever wanted to try your hand at programming one of the robots, you can now do that in simulation. The models are faithful reproductions of the physical robots in the SubT Challenge Systems Competition, and some are generated from high resolution photogrammetry scans. You can check out a full set of simulated platforms on the SubT Tech Repo.


Communication quality visualization.

For our final tutorial, we address what I believe to be one of the most interesting and demanding aspects of the SubT Challenge: multi-robot communication. I think most of us have had to deal with WiFi dead zones, either at our home or on the job, and they can cause even the best robots to lose communication and fail at their assigned task. The SubT Challenge takes this connectivity problem to an extreme by placing robots in environments that are hostile to most forms of wireless communication. Since the SubT Challenge courses are underground, they block out most terrestrial cell phone and radio signals and present an extremely challenging environment for WiFi communications.

Success at the SubT Challenge means quickly and accurately reporting the position of a number of “artifacts” back to a base station to score points. While it is possible to simply return a robot back to base to report its findings, that approach means retracing your path when every second counts. The challenging radio environment means that the competitors have to get creative with how their robots communicate, which includes having robots act as relays to route messages back to base. This strategy is particularly challenging as it requires that the team of robots must dynamically configure their own routing table. Other teams have opted to use “breadcrumbs”, small battery-driven repeaters, to maintain connectivity and report their findings. As we have discussed in previous posts the design of the breadcrumbs is rather interesting and worth reading up on. Competitors are also able to build a hybrid of these two approaches, using both repeater breadcrumbs and relay robots to build more complex network topologies. Our tutorial covers how to use the SubT Virtual Testbed to simulate connectivity and implement all of these strategies.

Relevant Links

Current Tutorials

Official SubT Challenge Resources

6 Likes